Samples enzymatic

Digest sample enzymatically and with acid extract phenol, phenyl sulfate, and phenyl glucuronide with ethyl ether... 

Nucleic acid analysis involves the determination of particular sequences of bases. Because of the low concentrations of individual sequences in most samples, enzymatic amplification processes such as polymerase chain reaction (PCR) must be integrated into the assay to enrich the sample for the sequences of interest. These amplification processes are never completely specific, and unless the assay is to rely solely on sequence selection during PCR, postamplification analysis is required to confirm the identity of... 

Flow injection analysis has also found numerous applications in the analysis of clinical samples, using both enzymatic and nonenzymatic methods. A list of selected examples is given in Table 13.3. 

Nucleic acid (deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)) probes utilize labeled, ie, radioactive, enzymatic, or fluorescent, fragments of DNA or RNA (the probe) to detect complimentary DNA or RNA sequences in a sample. Because the probe is tailored for one specific nucleic acid, these assays are highly specific and very sensitive (45). 

A lot of analytical techniques have been proposed in recent decades and most of them are based on enzymes, called dehydrogenases, which are not sensitive to oxygen and need cofactors such as NAD". The key problems which seriously hamper a wide commercialization of biosensors and enzymatic kits based on NAD-dependent enzymes are necessity to add exogenous cofactor (NAD" ) into the samples to be analyzed to incorporate into the biologically active membrane of sensors covalently bounded NAD" to supply the analytical technique by NAD -regeneration systems. 

A principal feature of GFC is its minimal interaction with the sample. This gentle technique allows for high recovery of enzymatic activity. For example,... 

If the luciferase sample solution contains a flavin-reductase, luciferase activity can be measured by the addition of FMN and NADH, instead of FMNH2. In this case, the turnover of luciferase takes place repeatedly using the FMNH2 that is enzymatically generated thus, the luminescence reaction continues until aldehyde or NADH is exhausted. A crude luciferase extracted from luminous bacteria usually contains a flavin-reductase. 

The theory and application of this fluorescence method have been discussed in detail by LePecq and others (3,8). The assay requires that there is sufficient ionic strength to minimize ionic binding (e.g., O.IM sodium chloride), that the pH is 4-10, that no heavy metals are present, that the fluorescence is not enhanced on binding to other excipients (e.g., proteins) and that at least portions of the nucleic acids are not complexed. These requirements can usually he met when dealing with recombinant products in some cases the samples must he manipulated to create the appropriate conditions. In the intercalative method of dye binding, proteins rarely interfere with the assay, and procedures have been developed to remove the few interferences they may cause (e.g., the use of heparin or enzymatic digestion of the protein 9). 

As is well known the difficulty of analysis of a sample increases as its complexity increases. Analysis usually commences with a rather nonspecific clean-up step and requires that the separation step that follows be highly selective and depends on a detection step that is as specific as possible. As the selectivity of detection increases there is also an increase in the reliability of the identification and it is possible to reduce the demands made on the selectivity of the preceding separation method. This is the case for radiometric and enzymatic methods and also explains the popularity of fluorescence measurements. The latter obtain their selectivity from the freedom to choose excitation and measurement wavelengths. 

More definitive evidence of enzymatic attack was obtained with 1 1 copolymers of e-caprolactone and 6-valerolactone crosslinked with varying amounts of a dilactone (98,99). The use of a 1 1 mixture of comonomers suppressed crystallization and, together with the crosslinks, resulted in a low-modulus elastomer. Under in vitro conditions, random hydrolytic chain cleavage, measured by the change in tensile properties, occurred throughout the bulk of the samples at a rate comparable to that experienced by the other polyesters no weight loss was observed. However, when these elastomers were implanted in rabbits, the bulk hydrolytic process was accompanied by very rapid surface erosion. Weight loss was continuous, confined to the... 

The aim of the work was the development of a technique to deposit enzyme LB films on the surface of small glass spheres and to test the enzymatic activity of such samples before and after thermal treatment. 

From the results of the urease activity test summarized in Figure 15, it is clear that the deposition procedure preserved to a certain extent the enzyme catalytic activity. Heating the sample before testing decreased the enzyme in the film by about 30% but did not eliminate it completely. The results of the activity test of two samples are summarized in Table 1 together with reference values for a spontaneous reaction without enzyme. It is necessary to underline that enzymatic activity on spherical supports was higher than the respective value in flat films, which could indicate that apparent catalytic efficiency was improved due to an increased area-to-volume ratio. 

The use of high performance liquid chromatography (HPLC) for the study of paralytic shellfish poisoning (PSP) has facilitated a greater understanding of the biochemistry and chemistry of the toxins involved. HPLC enables the determination of the type and quantity of the PSP toxins present in biological samples. An overview of the HPLC method is presented that outlines the conditions for both separation and detection of the PSP toxins. Examples of the use of the HPLC method in toxin research are reviewed, including its use in the determination of the enzymatic conversion of the toxins and studies on the movement of the toxins up the marine food chain. 

A more difficult problem to overcome is the overestimation of carotenoid concentrations in processed foods due to the usually more efficient extraction of carotenoids in such foods as a result of the denaturation of the carotenoid-protein complexes and cell damage. In addition, weight changes due to loss or gain of water or fat, enzymatic oxidation of carotenoids in raw samples, and leaching of soluble solids during processing should be considered. 

However, since pectins can be methylesterified and/or acetylesterified, sections were treated on grid with an orange peel methylesterase to remove the methyl groups or with NaOH to remove both methyl and acetyl groups. After the enzymatic treatment, all the primary walls of most of the samples bind the... 

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